Accuracy

Please select the most suitable grade of NOOK Precision Profile Rail
System for your application. For accuracy requirements beyond the
tolerances indicated or for any special requirements, please contact
NOOK application engineers.

Running Parallelism

Running Parallelism is defined as the error in the parallelism
between the datum planes of the rail and the runner block as the
runner block is moved along its entire travel length.

Differences in Height "H"

This defines the difference between the maximum and minimum heights
"H" of the runner blocks that are mounted on the same rail. (See Image 2 in Figure 1 Below)

Rail Accuracy Grade (units = µm)

C001 Ultra Precision

C01 Super Precision

C1 Precision

C3 High Precision

C5* Standard Precision

C7 Commercial Precision

Rail Length

Min (mm)

Max (mm)

-

315

1.5

2

2.5

8

16

52

315

400

2

2.5

3.5

10

20

57

400

500

2

3

4.5

11

24

63

500

630

2

3.5

6

14

27

70

630

800

2.5

4

8

16

32

80

800

1,000

3

4.5

9

19

38

90

1,000

1,250

3

6

11

22

43

105

1,250

1,600

4

7

14

25

50

125

1,600

2,000

4.5

8

16

29

57

150

2,000

2,500

6

9

18

30

60

170

2,500

3,150

6

10

18

30

60

210

* Stocked Accuracy - C5

Difference in Widths "N"

This defines the difference between the maximum and minimum
widths of "N" between each runner block mounted on the same rail. (See Image 2 in Figure 1 Below)

Rail Length

The maximum lengths of rail for NOOK Precision Profile Rails are shown in table below. Longer lengths can be achieved by butt joining rails.

Maximum length of rail track Unit: mm

MODEL NO.

MAX LENGTH

NH-15

3000

NU-15

1500

NH-20, 45, 55, 65

3000

NU-20 thru 55

3000

NH-25, 30, 35

4000

Unit = mm

Rail Straightness

To obtain high accuracy guidance, the rail itself must be straight.
It is very difï¬ cult to mount a distorted rail on a straight mounting
surface. NOOK rail manufacturing processes ensure straightness
for ease of assembly and long life. Distortion free end cuts are
achieved through an automated, wet, abrasive cut-off saw system.

Preload and Rigidity

For correct operation under complex loading conditions, the selection of
a suitable preload for linear motion bearings is essential. For extended
life and accuracy under conditions of vibration and shock, the best
results are usually achieved by using NOOK Precision Proï¬ le Rails with
heavy preload.

In general, if preload is applied to the NOOK Precision Proï¬ le Rails,
rigidity of the Proï¬ le Rail will be doubled compared to that of a
non-preloaded Proï¬ le Rail.

The preloaded condition is effective for operating loads of up to
approximately 3 times the value of preload. Therefore, as a guide, one
half to one third of the operating load should be considered for preload
and speciï¬ ed according to tables below. (See Image 3 in Figure 1 Below)

Selection of Preload

Preload

Conditions of use

Application

T3 Heavy

Heavy cutting or forming work with heavy impact and vibration.

Machining center

T2 Medium

Overhung load or alternate load applied.

Milling machines

Vertical axis of machine tools

T2 Medium

Medium cutting or forming light work with medium impact and vibration.